Helicopter control



Oct. 14, 1952 DONOVAN ETAL 2,613,751

HELICOPTER CONTROL Filed Feb. 4, 1947 4 Sheets-Sheet l ROTOR BLADE PITCH IN DEGREES FIG. 3

THROTTLE FIG. 2

ROTOR PITCH FIG.

INVENTOR.

ALLEN E DONOVAN BY HAROLD HIRSOH @AMQW ATTORNEY Oct. 14, 1952 A. F. DONOVAN ETAL HELICOPTER CONTROL 4 Sheets-Sheet 2 Filed Feb. 4, 1947 INVENTOR.

ALLEN F. DONOVAN w H M C 0 2.1 m 0w L O R A H% Y B 1952 A. F. DONOVAN ETAL 2,613,751

HELICOPTER CONTROL Filed Feb. 4, 1947 4 Sheets-Sheet 3 FIG. 6

III/1 5;

III/[Ill IIIIIIIIII/IlI/III/ INVENTOR.

ALLEN F. DONOVAN BY HAROLD HIRSCH IQAJMM ATTORNEY Oct. 14, 1952 A, DONOVAN ET AL 2,613,751

HELICOPTER CONTROL Filed Feb. 4, 1947 4 Sheets-Sheet 4 INVENTOR.

' ALLEN F. DONOVAN BY HAROLD HIRSCH ATTORNEY "trol are produced by the governor means. {system has -'as advantages that large adjustments ofthepower control, needed by reason or large Patented Oct. 14, 1952 .1 U NIT ED "ST PATENT OFFICE -2,613,751 p v HEIJICDPTER"CONTROL Allen nonovangKenmoi-e;and Harold Hirseh, .Biiffa'lm 'Ni Y;, assignors to-" Cur-tiss-Wright C'or- :poratiomracorporation of Delaware v,

n i licationFelirnary 4, 1947, Serial No. 726,260

the power control *meanswvith the meansf or changing the mean pitch of the iifting'"-'rotor blades.

The invention-contemplates alinkage connecting the rotor blade pitch change means-with the engine throttle valvecontrol; or-other power con- *trol; so that "the rotor "drive power will'be increased or decreased "inaceor'dance with increases "or decreases "in bl'a'depitch. The linkage "is -so -'arrangecl-that thepower"variationit'provides will "approximately compensate for change in drag of the blades incident'to' pitchchange.

" Superimposed upon this control "of pow'er in accordance With-"pitch changes "is a control by a device responsive to engine 'or'rotor speed. "This device, or governor,-controls the-operation of means whichadj'u'st the "linkage to change-the 'pitch versus power "relationship provided 'by the linkage. By this system coarse adjustments of the "powereo-n'trol' "result -direct1y irom-pitbh changes, and finer-adjustments ofthep'ower con- The rnagnitude change's in pitch, are madesimultane- -ously with the pitch changes, and-the *usual, un-

desirable effects of I a governor, '-nam1-y"1ag' in response and' hunting, are minimized. I

The governor means is preferably capable of being adjusted to difierent oontrol speedsy so' that t Y the "automatically maintainedrotor speed may be changed at 'w'illto any selected. value within' the operating range of theequipmeht.Therelationship of pitch versus powerrequired to 'maintain constant rotor speed-is; of "course, difierentfor 'difierent rotor speeds. "That is/for the" rotor speed in agiveneonditionof flight, say-"hovering or vertical ascent or descent, the requir'ewpower setting, "asrepresented by throttle-position; when plotted against pitch 'will "result in a distinctive curve and j there will 'be' "a 'fdiflerent such "curve for each-different rotor speed.

' For this reason 'thepresen't invention "contemplates "afipitchapowercontrol linkagesuch that adjustments "ofit will change itskinem'atics 'to cause it to 'respond'as'nearly as 'praoticable'"to the various pitch versus power curves otfthe "variousfrotor speeds within' th'e operating range.

In this way the linkage may be adjustedito produce the proper coarse movements. of the .power 'coritroL'fforvpitch changes, at any selected rotor speed. Moreover, such adjustment of .thelinkage may bethectedl by-the governor means inciden- -ISCIaims, (Cl. 170-13574 tally 'tdits "aetionpi superimposing aspe'ed responsive control uponthe'syste'm. Y

'The inventionfur'thercontemplates means 'for controlling "the pow'er independently v of the automati'c or governorcontrolwheneverdesired. This independent eontrolf'm'ay, if i desired,"be accomplished through the same linkage that is'em- .plo'yed for'theautornaticcontrol. In such case it-is-desi'rable that means "be provided 'to "act, upon "thechangeo'ver from automatic to manual 'ejo'ntrol; toretur'nthe' linkagefrom"whateverf'posi tion of "adjustment the 'g'overnorh'as"movecf'it; to a "predetermined position suited for manual op- "Stilliurthe'rthe inventioncontemplatesmeahs to "stabilize the-action of thetgovernor'or" to "minimize its tendency to huntaneutral speed "by alternately causing'undersp'ee'dfandoverspeed conditions, This "stabilizing "action may be effected 'by changing the 'control "speed lot. the

governor in proportion tothechange o'fi' li nkaige adjustment mad'e by the'governor. In'thisaction, known-as feedback, the speed setting of the governor is" decreased as the governor controlled means act to increase speed, and? the governor speed setting'isincre'ased as the eontroll'edrmeans act'todecrease speed. The "feedback contemplated in the present invention may be effected, if desired, through "the 'samelconnections .lto the governor :by' which the "latte'rs speed v setting is 'manuallyadjuslted. V e i The foregoing and other objects .and advantages of the invention, and-of the various com- *binati'ons and sub-combinations v thereof; will be "come apparent from the following description of typical-embodiments, wherein: I

Figure '1 is a v graph illustrating. =rotor torque variation with change of rotor blade pitche at.

different rotor speeds;

y Figure. 2 is .anothergraph illustratingthe varia tion 1-I1 engine t0rque:;de1ivered for *change m" throttle position rat-different engine speeds; flora typical helicopter,,-power:plant;

' FligureBiS still anotlier-ggraphdn effect eombimng the-graphs :of "Figures land '2, "showing for variationin'rotor blade pitch the E-changeiiin throttle position necessary to maintain :difiernt engine speeds; I v r A Figure fiisa diagrammatic 'viewillustrating the functional relationship of -the several Jelementssof the system invention; i.

Eigure5 is alongitudinal sectional viewthrough a res lient screw jack device-'comprising;.- a part ofthe linkage shown in Figure i;

in one embodiment of the but is free to slide along the shaft. 'c'onnect the adjusting collar lSfl-to each rotor Figure 6 is a longitudinal sectional view through the pitch change lever shown in Figure 4 Figure 7 is a sectional view taken along line 7-1 of Figure 6;

Figure 8 is a fragmentary sectional view taken along line 8-8 of Figure 7;

Figure 9 is a fragmentary elevational view of a portion "of the pitch. change lever as indicated by line 9-9 of Figure 6;

Figure 10 is a, wiring diagram for apparatus shown in Figure 4;

Figure 11 is a view similar to Figure 4 but illustrating a modified system; and,

Figure 12 is an elevational view of a linkage adapted to replace a portion of the apparatus shown in Figure 11 as a furthermodification of the invention. p

The torque requirements of a helicopter rotor increase above an initial value substantially parabolically with rotor pitch, the characteristics of the, torque versus pitch relationship for several different rotor-speeds being shown in Figure 1.

A family of curves for dilferent engine speeds showing the relationship between throttle opening'Tand torque deliveredis shown in Figure 2. By combining two such series of curves there could belobtain'ed a thirdseries of curves show- .ing the rotor pitch versus engine throttle opening relationship necessary to maintain difierent rotor 0r engine speeds. These curveslwould in g'eneral resemble the curves shown in Figure 3 .which were obtained experimentally from an actualhelicopter byv tyin it down and under conditions of negligible wind measuring the throttle position required at various rotor pitch fvalues to maintain engine speeds of the values findicated. Rotor blade pitch was measured in 7d grees while throttlemovement was measured interms of linear displacement of a flexible slid- "ingfiw'ire connected to the crank of the engine throttle.

In Figure 4 is illustrated a system embodying the, present invention.

v The system employs a mechanical linkage between a pitch change lever l! and a throttle arm l2 by which the air intake and hence the power of the helicopter engine "[0 is controlled substantially in accordance with pitch versus power relationships shown in Figure "The pitch lever II is connected by fitting 13 ft!) a'rock shaft l4 towhich is pinned the arm "Main turn" connected by sliding wire M2 to one arm of a bell crank I44. 'Theother arm of the bell crank is connected by a link I46 to cl nc -rotating collar I48 which is free to slide "0 1l the lift rotor-drive shaft 26 and acts through antifriction thrust bearings-on'th'e pitch adjusting collar I50, which is keyed to the shaft 26, Links I52 blade at a point spaced from the blade axis "(one suchv linkand one blade being shown in thepdrawin'g) so that sliding of the adjusting :collar along the shaft results in'change of the blade pitch. The 'pitchcontrol linkage is arranged in such manner that upon upward move- .mentiof the :handgrip of the lever the mean pitch of the blades will be increased. An arm .15 .on:.the rock shaftJis pivotally" connected to the lower arm of a bell-crank lever I6 by an adjustable length link I? whose details are shown a slot 19. Plate I 8 also has a slot, designated .21.; v:Aroller ona pin-22 attached'to one end of ziaflexible sliding wire 23 extends through and defines the pointloi intersection of the two slots.

guide tube 24 which is pivoted to plate I8, and at its opposite end is anchored to the engine In while the cable 23 is connected to the throttle arm l2.

It will be seen that as the pitch lever is elevated or lowered to respectively increase or decrease the pitch of the rotor blades, the linkage described will function to open or close the throttle. In such action levers I5 and IE will move clockwise and throttle lever 12 clockwise for throttle opening movement. :The degree to which the throttle is opened for a given angular movement of the rock shaft l4 depends upon the kinematics of the linkage system, which may be varied to produce the desired pitch versus throttle relationships by changing the angular relationship of the several lever arms and also by changing the contour of the cam slot 2|. The latter acts, as bell-crank lever It moves about its fulcrum, to move the roller on-pin 22 inwardly or outwardly along the slot I9 thereby varying the efiective length of the'upper arm of the lever l6.

The kinematics of the linkage shown are such that by extension or contraction of link I! the pitch versus throttle relationship provided by the linkagewill change from approximate adherence to the curve for one speed to similarly approximate adherence to the curve for another speed (see the family of such curves, Figure 3). Thus extension of the link i! will not only partially close the throttle but will also change the angular relationshipbetween levers I5 and It in a direction such that the linkage will ap-,

proximately maintain a pitch versus throttle and especially for pitch settings and throttle openings near those required for hovering flight,

these being more important than for other speeds and flight conditions. It will beunderstood, of

course, that only approximately correct throttle positions will be produced by the linkage thus far described in detail, since, for one thing, such variables as engine emciency, air density, loading condition, forward speed of the helicopter, etc. affect the finer throttle adjustment required to maintain Withinreasonably close limits a given rotor speed for a given blade pitch angle. The

means for effecting such fine adjustment by exe tension and contraction of the link I! will now be {described A speed responsive governor 25, of any suitable type such as that shown schematically in Figure .10, is arranged to be driven from the engine shaft, or, possibly, from the lift rotor shaft26, as through gear I25. Through suitable'means, such. as the electrical circuit arrangement to be later described, switches operated by the governor serve to control the operation of a linkage-adjusting electric motor 21. The efiect of the governor is to cause the motorto expand.

link 1(reducing the throttle opening) if the drive speed exceeds by a certain margin the governor control speed setting or, if the drive speed is under the set speed by a similar margin, tocause reverse operation of the motor to con tract link 'I 7 and so open the throttle. The speed mo'r'ayaoi setting ofthe governor is 'addusted i-by angular movement cit-arm 28, -which may 'be efie'cte'd by turning a flexible shaft :29 to expand or contract a serew deck- 31 that is connected td the T he motor 2 -throug'h a' vvorm 1 :t28=: tast ton the motor 'shaft 4-21 :anddriving a v worm zwheel liilkeyed to 'a 'shaf t 32, or through' any other suitable reduction :gearing, dri-ves izthe shaft-32 whichwarries pinions m andafld which respectively meshimithsrring gears :35: and -3B: of :differential gear units :i'leand L38. Zone of thezsun gears ::of uniti 38 isgsecuredzto ifiexible :i's'haft'; 2 9, while thelother' sunsgeariof ztheumit: isiatta'ched to anotheriflexibleshaft :39. .il'helattertmaylbe turned by a .mand crank'.'4 I :through: speed tin- .creasingisgearingt-zfll Itsovill bezis'eensthat. when thezmotorsishaft :32 zzand. ringliigear: tionary, turning "of :the a crank so].

36 tiare sta- 'sha'fti zaz and. thereby: adjust: 'sthe sneede'setting I ofis'the governor. .Or,;if.;the handlel'i4 l...isoheld stationary ns :zititusuallyeis :by. suitablerifriction means mot-shown), whentitiislnotdoeingmanually operated, rotation of ;the mingagear bytthe motor 5 willaalso turnethe :shaft 29 toladjustuthe governor' speed :osetting for a ypurpose to he t; more; fully cexplainetdlhereinafter. .lOne 551111;, ggear vof .the difierentiahunitr31 secured to rat-shaft ;43 .Iwhich is ;rotated ..through .a flexible shaft-A4 iandmpeed increasing; gearing 4.5 I:by r manual turning-9. aha. throttle operating grip vL5 ,on, the, ,pitch .leverJ l-. .The grip Jmay be :so operated only when;:;the governor-control isgtturnedzofitandis locked againstturning gwhen the. governor control .is' turnedmn. I The. other sunggearr'of the unit :31. is secured :to one end of a flexible shaft 4.0 whoseopposite ;end is. connected to the screw jack 11. 'By the arrangement described it willibe seen that either operationof the motor 211- 'or turn-ingv of the :throttle grip on outerrand e inner telescoping ycasing sections .146 and 41, pivotederespectively; to tleversplfi and iwillebeguaftfectiverthrough lzthezcdifierentialrunit-ufifi; to: turn slots. As shown in Figures;-6Y=and;9. ;the:screw 1.5 and the :zsection A .rjournallingqa ,tscrew, 48 v whichtis ;-secur ed;to. the end of lflexiblezxshaftjfl. Threaded f to thescrew and Lslidable, but none m t e I n' c' sinesse t on-J- 41 1 tubular member 43 spring 5]; compressed ibetween annul-a-r changes, at I the ends ot memhers, 4] and 43 causes these members ,to normallywmove as ;-.a unit. =re1ative ;tosection 146 to ;;shorten ;:.or vlengthen thealink I] as the shaftyfifigsandascrew .48-.are rotated..,,, Also when .the.-shaft andzscrew 'are'stationarv he spring-:5 l' t ermally-causes the fia iswzrigi d with ian iinsulatorzii armountediocn-ia xtub'eifi I: whichiis 'slidableaancifrotatablesupon:rod 1552mresp'onsexto manual movement oftr'rod u58; Theflnsulatingiplughassguide.holeszionthescon- :conta'ct 1.63. Either contactzmayqloe engaged by pin 51. by appropriate.zturningiandalongitudinzl im'ovement ro'f theiinsulatoruifirbyameansro the thumb'piece:onarod;58.: a ;,r. o,

.Theutub'ehsl andiinsulator 659::ar wardly Tito: the left trinuFiguretIG nto: close one of; contacts 62 and 63 againstirtheipim51. ,;byo9. 1

light spring, 64 rwhich actstxbetweenzvasshoulder on tube GI and a collartohgrorkfiairhichosupportssscrews 165. A heavierzspring'tfifiinirgesbthe 'collarzoutwardly :along rod.155. to:move Ltherheads of screws a 65 :into; thexrrestricted:portions i of Lop.-

;p'osed;keyhole;slots 61.. that :are :formed; inztubnlar part-.52, for: at t leastcto' tmove .i.the ESCILG WiZhB BldS against one of, :the Lend walls 615 of. the keyhole heads were guided for purely .longitudinalzzimovement by elongated.slotsqfiainfpart; 53.3. I

I v When the .rod 58 is; actuatedgtoxcdepressrin .s'ulator' 5'9 and vthen allowtitto; return withgp'in '51 against contact 62 the S016W.'1 heads ifil'r will be held in thezwide portions :of the keyhole-slots 61,1150 that theyhandwgrip $54: ands xarmvifit-l are freetto be rotated. :to turn-.the flexible: shat.a-.44 to whichwtheyi are connected,;zthereby; manual- I v1y operating the. throttle my sexpandingz zorzcon tractingthe link ll. .However,,when "the P111215] is moved into. contact--with contact element 63; which'will be doneonlyxwhen .the, grip' ;;54 is turned -tojthe correct p'ositionto align the screw heads ,65 with theirestricted portions 9f .the keyhole slots, the sPring GG will 'urg the. screw heads into that portion of the r-slots. nd

thereby lock the manual throttle .controlzagainsit movement.

Reference will now be; made t o 'ithe "electrical,

seemed with the extensible tea mate linkage 'to cut on the motor when either limit I condition-of the linkage is reached;"' and switch means comprising twoswitches 15and'ffl -and an actuator 14 therefore operated 'by' the- -motor td adjust the "system for manual or "automatic operation. 'As shown'in Figure 10," the electrical the engine, asolenoid switch"-1 l for 'thj'e "taite'i link-[1J0 fnnctionvaswa vrigid unit'in :transmittingmotion iromleveni-S; to lever IB, HOW:-

ever the spring permits egpansion of ithetglin'k I I upon .the occurrence of largenmovementstof lever, l 5 than; those I causing limit movement .Of

lever is in aclockwise direction. Accordingly the pilot may move the .pitch lever to increase irotor"blade;pitchangle beyond that in which thelthrottlewalveis fullyjopened. I -:vAseshowniirnfiigure Jiithenpit ho'lever' H'mimay comprise ats'hort tubular 31 311131152 on. whichlis .rotatably A mounted a tubulariarmz 53,; with 1 hand grip; 54 and 'a rodgs55l coaxial of ';the.,1arm. and rotatable with it. 'ilihe;;arm;553zand'crod :55;:- iare connected by a; plng-z 5G3 supporting tanrelectrical contact-39in 51; andhaving "an ,;arcuater;opening .througlirwhi h extends 1-3;; i1ock.: ;operating;;roduSB pp tnugnp -p ece at itsliorward end..;:.fIhe:rod

motor, a 'manuaIIypperated switch aflforithe starter circuit, and'ywires [Bil -to .l'I 6;'{incl-usive,

which I serve to connect "the various switches;

motors and energy source. These wires; "othe'r than 1 those involved in also showndn Figure I II I I I As shown in Figure i"the'switohinismounted on tplatell 8 and is adapted "to- 1me engaged and opened I by bell-crank lever l6 "when the Flatter is moved to its limit position corresponding: o

full openthrottle and sijmilarlir 'the switch 13, also mounted on plate |8, is 'adapted -to be opened by the bell-crank in 'its 'l-imit position correspond I inglto the'idling or closed position of the: throttle.

vThe motor 2l'through a suitable. reductiongeari- "ingcperates the switch actuator-l4 :whi 'h in its limitof thecounterclock-w ise ('as' view'ed' Figure.

A) movementengages each of two switchesi 15 and 11I6';-ropening itherswitch which'i Isl-normal- 1y;c1osied and closingithe switch 16' which; is normally open.'.. The .motor may be. of any suitable reversing. typera but: in the simplified wiring diagram, Figure, 10, comprises one field winding dizwhich is engaged for -operation in a direction to contract thevscrew-jack l.1,i'.'e. to open" the throttle; andfii-another .field winding18 for reverse: motor. operation to expand the. jack" and close the throttle. The governor exerts its con-- "trol by movement zofxswitch. 19 which .is open I when the rotor. driveis on speed, is closed against its lowerscontact. when the drive is'overspeed and is closed. againstv its upper contact when the driveis underspeedta v With the switch contacts. 51, B3 closed and the manual throttlecontrol locked, the governor will "--.operat'e.:; .to-iautomatically maintain rotor speed 'atrthevalue selected .by manual setting .of: handle 41. this automatic control action,

=current fromvthe battery69 will pass through thezgroundandcontactsl 51, B3 to the governor operatedswitch .19. (.If the rotor speed. is within the on speed. rangepthe': switch '19 will be op'enso that nooperation of motor.21 can bccur,. but for an underspeed condition theswitch -191-'will close? againstits upper contact so that the? current will pass through closed switch 12 and the :motor field windings '11, the motor armature iandfreturn :to the. battery, thereby causing motor 'operationdn a direction to contract jack -.I1 and furtherfi'open the throttle. operation will continue until such time as the: governor 'signals an onspeed condition of the i otorby openingthe motor circuit-at switch 19; -S 1milarl y if-an overspeed signal is given by 'the g'overnor switch 19 closing against its lower contact; the current will-pass through closed tchf-13,1 hermally closed swit'chflfi and the motonfieldjarmature 18. This'will result in the motor operating in a direction to expand the jack ll and Close the throttle.

It" will bemnderstood that if during. throttle opening movement of the motor (field coil 11 energized). the open throttle limit position' o f bell ec'rank'l a isfreached, the'latter will engage ahd'openswitch" 12't0 cut ofi energy'to the motor. Similarly. if duringv reverse movement of (the motor the closed throttlejjlimitjis reached, the

pen switcl' li13 to I de-energiz'e ellcrank wilj'lo otbreirtuitg I g I If themanualfthrottle control is now unlocked nt'acts' ilfand' fi'fare closed by manipulattion of fontrql rod 58, the motor i will operate the Jack -l1 to. the correct position for manual pperatio and will then automatically become inoperative Current passing from the battery through the ground, the normally closed contact 15 andthe 'field. winding 18, cause operation of the gmotor to fully extend the jack I1, this bein theiia ositi c sen r ual t ottle operation. When the motor'has turned a; num- .1361 or revolutions sufiicient to bringthe jack to this condition if ,the manual throttle grip is in closed positionthe switch actuator.

.jtillhave, moved to-its limit of counterclockwise motion to a positiongwherein the normally closed switch 15; isiopened andthe normally open switch ihdtofrffzi cutloil and the-jack l1 will now be .operablexonlyasa; result of manual twistingof automatic for governor: operation the circuit for solenoid -.switch 11 ;is open at switch 16.; :It will be understood that- ,when the system is setfor automatic operation the governor-nor mally need make only relatively small or fine adjustments, coarse adjustments being made by the mechanical linkage connection between the pitch leverand, the engine. power or throttle control. Consequently the governor may beof a type responsive to minoryspeedfluctuations which greatly increases its-accuracy in maintaining the selected speed. Nevertheless since a governor can respond only ;to ofi speed conditions of therotor drive and will continue "to take correcting. action until the set. speed reached, the result will ordinarily be a continued alternation of overspeed and vunderspeed conditions known as. hunting. Varioussmeans may be employedto reduce this efiect, thepar- .ticu'lar means, known as feedback; employed in the presently illustrated embodiments operating by "changing. the control speed setting of-"the governor inth'e direction opposite'to the direction of. thespeed correction being? made. .Thus if the rotor is overspeed so that -the governor is:causing. the motor 21 to operate in throttleclosing direction, the governor speed 'setting is proportionately increased through gearing '34, 36, 38, flexible shaft 29,-and screw jacktl. Or, if the motor is operating to increase throttle in response to an underspeed signal from the governor, the governor speed setting is reduced by the feedback system. Various amounts of feedback may of course be used, but it has been found thata change ofthe governor speed settin of approximately 3%, for a movement of the motor 21 sufficient to move the throttle from full open to full closed,-provides a satisfactory result. v

.The system illustratedin 'Figure'll is similar in principle to that hereinbefore described and ifdesired may employ similar electrical operating circuits and protective arrangements.

. It-differs primarily in that differential lever ar- ;throttle gr-ipg54: 011313116 pitch; lever. ,It--.;will be tnqtedthatonlysw n e system is se fo ma u l p ration-tor the throttle can the circuit -,-for. the engine; starten: motor :10 be. energized. When .on

rangements and flexible sliding wires with flex- :ible sheathes are employed instead of a difierential-gearing arrangements and flexible shafts shown in Figure 4 In Figure. 1 =1--a'pitchlever -81 is connected to a pitch change rock shaft -'82 'and has a rotatable throttle grip 83 which through acrank 84 can impart motion tdfiexible sliding wire 85. The latter is supported' in a flexible casing or'sheath that isanchoredat its 'endsto the lever BI and to afixed part 86 oi the-helicopter Alever 81 on the rock shaft is pivotally connected by a'1ink=88-'to a bellcrank lever 89 having its fulcrum upon fixed structure and arranged to transmit motionto a flexible sliding wire 9| which-is-attached at 911130-1119 fiexibldtz'ase as of an'oth'er flexible sliding wire 94. Wires 85, 94 and also the free end of a screw-jack 95 are pivotally connected toalever96.-

The wire 94 is connected'by a pivoted link :to a member 91 which is-pivoted to fixed structure at 99 and has a camslot98 that is similar in purpose" to the cam slot 2lpreviously described A pin lfll having a'roller in slot 98 is .carried'by a link I02 which is" guided by rollers I E13 andalso by"'the control arm 104' of-the engine throttlaindicatad at I05.

The screw-jackWhi0h is pivoted to fixed structureat lfl is adapted-to be extended or contracted by operation of a motor- 108 which :is connected to the 'jadk' by suitable reduction gearing I08 and fiexibleshaft I09; Expanding or contracting motions of the jackare'transmitted through'a. flexible slidingwire III to a levertll'2 which is connected byanother flexibleslide wire I I3 to. a manually operable governorspeedset-lever II4.- Intermediate of the connections towires III and .I I3 the lever H2 is -.pivoted to a link llewhich is also pivoted to anarm II6. This arm extends from a governor. H1 and is angularly movable upon move-- justments of throttle position or engine power;

will be-made by movements of lever M to vary therrotor blade pitch. In this action the end of; slide wire 94 and, its flexible sheath 93 ad'-' jacent thecam member 97 will bemoved asa which has-afixed fulcrum-and-hasTits-remain- The latter -may unitwithout any movement of the Wire withinv the: sheath orany-movement of the lever-96. Assuming first that the throttle grip is locked, orin any eventisnot turned, fine adjustments of: the throttle will be made by expansion or contraction of the jack by .the motor as the resultof overspeed' or-underspeed signals of the governor lI-I; The control speedof the governor may be varied manually by operation of lever- H4, and it may be variedby feedback through-flexible slide wireI I I. Such feedback may, be: approximately at the-same rate and. accomplish the same purpose on thefeedback described in connection with the apparatus shown in Figured. ,J

"With the governortand motor' shuts-off and the. :throttle grip 83 freed for'manual: operation, thepivot between the-screw jack 95 'and}lever Ni-may act 'as the lever fulcrumc. Turning. of the throttle grip, :translated into linear1'move-= ment of. wire: 85*by the crank 84, will therefore resultin: movement of; the unit 94'; in sheath' 93 to change the effective length. of the 'linkage be tween the pitchjlever: and throttle; and to there by'make fine adjustmentsof'thelatter;

In the arrangement of Figuremll. the kinee .matics of the linkage: between-the pitch lever and throttle are preferablys'uch'thatx expansion or contraction respectively willv cause the pitch versus throttle relationship to change to that. approximately correct; for a' lower speed, or: for a higher speed, or; in other words; to change from approximate adherence. to on'ecurvein' Figure. 3; to the curvethereini for" a lower or higher; speed. In this way a change in the governor speed setting, by moving lever H41"; willfresult inE tine:- mechanical linkage being; adapted tothe new speed setting.

There is. illustrated in. Figure 12 avmodifiedlinkage which maybe employed, for: example,- between the .bell-cr-ank-ts and the; cam: link 90s of. the structure-shownin Figure! 11 130" replacethe flexible wires-..9.l .and 94, jack-95 and-,leyer 96.' Pivotedt bellecrank '89Qis a tubular, casing I 2'I' in, which. is'lslidably mountedthe, body ofta 's-crewjack, I221 The. opposite end. otthejafckiis'pivoted to; one armof' afbellcrankmlzi cludinglm'eans. for; causing readjustment theapparatusshownimFigure:11.

4 ual .control.

said linkage to more .closely maintain co'nsta rotor speed, a' manuallylioperable, element ing-arm epivoted to the link; 90. 7 The -j acle. may. beextended orycontracted through rotation; of the flexible .shaft .4 I19. by the motor drive means..

' hereinbefore .descr-ibedg- The flexible. vslici'elwire.

for' effecting. manual throttle adjustment is.

connected at" I24 to, the =j ack :body, '.while;

flexible sheath. is connected at I25. toI,the.Icas ingfl-I2IL' As-will be apparent, extensionor cone. tractiomof the linkage betweenelements. ,89...and 9 I maybe effected;- with thisgarrangement eit if. manually.Or autQmaticaI-ly by the governor conI-I, trolldmotondriven .jack -tdproducerin another.- way substantiallygthe samefresult-attained with;

Itwillbe understoodthat the.link gebetween; thepitch levee andthrottle. or}. o.ther; power. con-I, trolmay be-.altered ;in.variousf ways-and.also:that.v various electricahandr-other typ esmofmeansireg sponsive 'to-rotorspeed may .be employedto ef'. fect the-efinerf adjustments of: .the glin-kage}. cone: tem-platedbythe invention :.to be superimposed upon the coarse .adjustments made..bymecham} ical linkage. For example it may be considered. in Figure- 11 that the motor Iilfiflisqhydraulically.

I operated and that the governor. I I 'IQis. a gover-e. nor valvefor controlling.themotor; or, to ef feet essentially. the same result, the noton [05. and s-crewjack may bereplacedby a hydraulic" strutor jackoontrolled by such a governonvalve.

These andwvarious other modifications which;

will readilyoccur to. one skilledin the art. may.

be made without departing from .the spirit of;

the inventionor. from thescope of the appended claims. I

Werclaim: I

v 1. Inahelicopterhavinga power controllari'd I a manuallyoperablelroto-r. pitch control, the lcombination therewith. of. an. adjustable linkage gfor coordinating said. controls; to cause'f-the power. control settin to correspondapproximately with: thesettingrequired tomaintain. constant." speed at various rotor blade. pitchv positions drive speed responsivemeansandmeans trolled thereby. for adjusting. said linkageito more. closely. maintain constant rotor speed, a n riari I uallyoperable. element,..for adjusting said.. link .age, means for.,rendering;said element irioperafj-- tive andv means. fonrendering .saidi element, 0p

' erati'u'el and for simultaneously.disconnecting aid speed responsive. means. from, .the 'meansf c n}.

trolled. therebysaid, '.lastrnentioned meai-isgi linkage, to a. predetermined. conditionfor v I 2. In a heieoaenaaagt;r t r drive power;

control-and amanually. operablerotor pitch, control, the combination-therewith Of. an adjustab linkage for. coordinatingsaid. controls togcau'se Y the power setting. .to correspond; approximately; with the setting required. to maintain constant,

rotor speed. at the. various rotor bladespitch p tions, a. drive speed responsivemeans randfp operated. means controlled ther'eby for. adjusting.

adjusting said linkage, means' 'for rendering fsa element. inoperative, ,and] means. for rendering;

said element .operative and for simultaneously rendering ineffective the, controlof saidp'owei operated means 'by'said. speed responsive means-, said. last-mentionedmeans ineludingfrneans' for] eausingoperation of said power operatedmeans' to. adjust the linkage to .a pre" .ete1 "mined; con tionfor. manual control; J

ing said linkage, means for rendering said element inoperative, means for rendering said element operative and for simultaneously rendering ineffective the control of said power operated means by said speed responsive means, said lastmentioned means including means for causing operation of said power operatedmeans to adjust the; linkage to a predetermined condition for manual control, and means responsive to the power control. reaching .either limit position thereoffor rendering said power operated means inoperative.

4.' In a helicopter having a rotor drive power control and a manually operable rotor pitch control member, means including a device responsive to rotor speed and operatively connected to said power control, a manual control element carried by and movable relative to said pitch control member and. operatively connected to said power'control, means for locking said manwill control element in a predetermined position relative to said'pitch control member, and means for simultaneously unlocking said manual control element and rendering the speed responsive device ineffective to operate the power control.

5. 111 a helicopter having a rotor drive torque controlel'ementand a rotor blade pitch'control system including a pilot operable element for operating .said system to vary the blade .pitch,

the combination therewith of an operating connection between said pitch control system and said'torque control element, said operating con nection including cam .and cam follower means arranged to move the torque control element'approximately to .the setting thereof required to maintain a selected rotor speed at any of various blade pitch positionsselected by operation of said pilot operable element, said operating connection including adjustable meansto vary.

the setting of the torque control element relative toublade pitch. position, mleansresponsive to rotor.

drive speed and means operatively interconnecting said speed responsive means and said adjustable meansto effect adjustment of thelatter in response to deviations from said selected speed and in a direction to maintain said selected speed.

from said selected speed andin a maintain said selected speed.

7. In a helicopter having a rotor drive torque control element and a rotor blade pitch control system, the combination therewith of an operating connection between said pitch control system and said torque vQ ntrol element, said op crating connection including means arranged to move the torque control element approxi-' mately to the setting thereof required to maintain a selected rotor speed at any of "various blade pitch positions selected by operation of pitch control system, said operating connection including adjustable means-to vary the setting of the torque control element relative to blade pitch position, a governor responsive to changes in rotor drive speed, and means'controlled by said governor and operatively connected to said adjustable means-for effecting adjustment thereof in response to deviations from said selected speed and in a direction to maintain said selected speed;

8. In a helicopter having a rotor drive torque control element and a rotor blade pitch control direction to I system including a pilot operable element for operatingsaidsystem to vary the blade pitch, the combination therewith of an operating connection between said pitch control system and said torque control element, said operating connection including means arranged to move the torque control element approximately to the setting thereof required to 1 maintain a selected rotor speed at any of various blade pitch positions selected by operation of said pilot operable element,:said operating connection including 'adjustable means to vary the-setting of the torque control element relativeto blade pitch position, a governor responsive to changes in rotor drive speed, and means controlled by said governor-and operatively connected "to' said adjustable means for effecting adjustment thereof in response to deviations fromsaid selected speed and' in a direction to maintain said -selected speed.

9. In a helicopter having a rotor drive torque control element and arotor blade pitch control system including apilotoperable element foroperating'said system to. vary the blade pitch, the combination therewith of an operating. connection between said'pitch control.system' and said torque control element, 'said' operating connection including means arranged to move the torque control element approximately to the setting thereof required to maintain a selected rotor speed at any of various :6." Ina helicopter having a rotor drive torque control, element anda rotor blade pitch control system, the combination therewith of an operating connection between said pitch control system-and said torque control element, said operating connection. including variable ratio means arranged to move the torque control element approximately to the setting thereof required .to

' maintain a selected rotor speed at any of various blade .pitch positions selected by said pitch control system, saidcperating connection including adjustable means to vary the setting of the torque control element relative to blade pitch position, i means responsive to rotor drive speed and means i operatively interconnecting said speed responsive means and said adjustable means to effect adjustment of the latter in response to deviations blade pitch positions selected by operation of said pilotoperable element, said operating connection including adjustable means to' vary the setting of the torque control element relative to blade pitch position; means responsive to rotor drive speed operatively connected to said adjustable means to effect adjustment thereof in response to deviations from said selected speed,

and manually operable means also operatively' connected to said adjustable means for adjustment thereof.

10. 'In a helicopter having a rotor drive torque control element and a rotor blade pitch control system including a pilot operable element for operating said system to vary the blade'pitch,

the combination therewith of an operating connection between said pitch control system and said torque control element, said operating connection including; means .arrangedto move thev torque control. element approximately to the setting thereof. required to maintain a selected roto'rspeed at any of various blade pitch positions selected by operation of said pilot operable element, said operating connection including adjustable means to vary the setting of the torque control element relative to bladepitch position, means responsive to rotor drive speed for actuating said adjustable means to thereby superimpose a speed responsive control upon the drive torque control provided by said operating connection, manually operable means for actuating said adjustable means, and a differential connection between said speed responsive means,

said manually operable means and said adjustspeed at any of various blade pitch positions selected by operation of said pitch control system, said operating connection including adjustable means to vary the setting of the torque control element relative to blade pitch position, a governor responsive to changes in rotor drive speed, means controlled by said governor and operatively connected to said adjustable means for effecting adjustment thereof, manually operable means also operatively connected to said adjustable means, and selecting means for rendering either said governor-controlled means or said manually operable means operable to actuate said adjustable means and for simultane ously rendering the other thereof inoperable.

12. In a helicopter having a rotor drive torque control element operable between predetermined limits and a rotor blade pitch control system including a pilot operable element for operating said system to vary the blade pitch, the combination therewith of an operating connection between said pitch control system and said torque control element, said operating connection including means arranged to move the torque control element approximately to the setting thereof required to maintain a selected rotor speed at any of various blade pitch posilimits and a rotor blade pitch control system I including a pilot operable element for operating said system to vary the blade pitch, the combination therewith of an operating connection between said pitch control system and said torque control element, said operating connection including means arranged to move the torque control element approximately to the set- 14 ting thereof required to maintain a selected rotor speed at any of various blade pitch positions selected by operation of said pilot operable element, said operating connection including a resiliently preloaded play connection to allow the pitch control element to overtravel the torque control element when the latter reaches a limit position thereof, said operating connection including adjustable means to vary the setting of the torque control element relative to blade pitch position, means responsive to rotor drive speed operatively connected to said adjustable means to effect adjustment thereof, manually operable means also operatively connected to said adjustable means, and selector" means for rendering either said speed responsive means or said manually operable means inoperative and simultaneously rendering the other one thereof operative to actuate said adjustable means.

14. In a helicopter having a manually operable rotor pitch control and a power control, an adjustable linkage connecting said controls, a governor and means normally connected to and controlled by said governor and connected to said linkage for effecting adjustment thereof,

a manually operable element operatively connected to said linkage for efiecting adjustment thereof, means for selectively rendering said element inoperative or simultaneously rendering said element operative and disconnecting said governor from said governor-controlled means, said last-mentioned means including means for causing said governor-controlled means in response to said disconnecting operation, to adjust said linkage to a predetermined condition.

15. In a helicopter having a. drive .power control and a rotor pitch control; the combination therewith of adjustable means connecting said controls for effecting coordinated increase or decrease of drive power with increase or decrease, respectively, of rotor pitch; drive speed responsive governor means adjustable as to control speed setting and operatively connected to said adjustable connecting means for effecting an increase or decrease of drive power in response to a deviation of the drive speed, under or over, respectively, from the set control speed; and means connected to and actuated by said governor means to effect an increase or decrease of the set control speed in response to a deviation of the drive speed, over'or under, respectively, from the set control speed.

ALLEN F. DONOYAN. HAROLD HIRSCH.

REFERENCES orrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,115,485 Dodson Apr. 26, 1938 2,209,879 Focke July 30, 1940 2,217,364 Halford et al. Oct. 8, 1940 2,317,341 Bennett Apr. 27, 1943 2,318,260 Sikorsky May 4, 1943 2,343,378 Kieser Mar. 7, 1944 2,364,116 Whitehead Dec. 5, 1944 2,378,558 Kalin June 19, 1945 2,399,685 McCoy May 7, 1946 I 2,517,150 Webb Aug. 1, 1950 

